Sorry that I did not post yesterday, but I got stuck bingeing Criminal minds (eight episodes!). I also was torn about what to pick for D, since there are some great things with D: Dill, Durian, Vitamin D, Dehydrolipoic acid, Dimethylosulfoxide...But I felt that I need to take a step back, and explain two big essentials. So for today and tomorrow, we will be stuck with D.
D is for Digestion:
Mouth: We chew our food to make it smaller, and start digestion. It does not really matter how much we chew, it is okay if you wolfe your food down or if you prefer to fletcherise it, since your stomach will do the rest later. Our saliva is the key here: It lubes up the foot so it goes down smoothly (mucines) , it has some enzymes it it (lipases if you are a toddler, to digest fat in milk, else mostly ptyalin, to digest carbohydrates). Fun facts: if you chew starchy bread long enough, you can taste the sugar that the enzyme cuts off from the starch. Another one: use saliva or better, toddler saliva to pre-treat food stains when you have no stain remover around.
Your saliva also has a mild painkilling protein in it, antibodies, and antibiotic proteins like histamin and lactoferrin, so lick your wounds for disinfecting and faster wound healing, no shit.
Saliva is also washing stuff away from your taste buds.
Esophagus: It is more than just a tube down into our stomachs. It is a muscle, actively transporting stuff towards the stomach. If you do a headstand, you can still swallow. It also has a sphincter to prevent stuff from coming up again. But sometimes, shit happens, and so some people have an inactive sphincter or one that is unable to close (If my mom would turn me on the head as a baby, the milk would just pour out again), some peoples sphincter is unable to open, sometimes the esophagus is not a tube, but has more blind passages. It can be damaged, which is one of the many problems when you have to do radiotherapy: it hurts like hell when you have to swallow because the whole thing can be inflamed. Additionally, the esophagus cools down your food so the stomach is not damaged, or it heats up cold food, too.
Stomach: more than just a bag of holding. It is a muscle. Actually, the whole passage is a muscle, from top to bottom, but very specialized. If you overeat at a party, your stomach hurts because it is not used to being stretched like that. After Christmas, you stomach has adapted, and you feel empty and hungry even after normal sized portions, because you need to train your stomach back to a smaller volume. It also actively grinds your food down into a pasty liquid. No matter how little you chewed, this strong badass will totally wear it down. Finely.
Additionally, the stomach makes acid: after food, it can go down to a pH of 1-2. This dissolves most bacteria (some assholes survive, like helicobacter pylori, who makes ulcers and cancer, but also some lactic acid bacteria, our friends and probiotics). The strongest stomach acids have vultures, who can eat everything. The stomach acid is there to disinfect food, to prevent it from fermenting while it is still ground down, to dissolve proteins and to prepare Vitamin B12 for uptake. If you take proton pump inhibitors (Losec, Prilosec), you can develop a problem here, because B12 is depending on a low pH. The B12 (cobalamin) needs to be bound to Intrinsic factor, a transport protein, which is dependent on pH and trypsin (protein digestion enzyme in the stomach, pH dependent). A few more details on acid reflux: Acid reflux is not always caused by too much acid. Sometimes it is caused by not enough acid. For example the bacteria helicobacter pylory neutralises stomach acid by producing ammonia. The sphincter that separates the stomach from the small intestine (Pylorus) checks the chymus (the ground up contents of your stomach) for pH and particle size, to decide what is ready to be digested, and what not yet. Only very acidic stuff can pass. He opens the door approximately 20-30 minutes after you ate, to check on things. If the chymus is not acidic enough, he slams the door shut, and the chymus can be pushed back up into the higher parts of your stomach, and eventually into the esophagus, and cause heartburn. Also, if you took antacids for too long, the body will think you don't need your protective mucus stomach lining anymore, which makes the stomach more sensitive to pain and acid damage. To increase stomach acid, eat something with proteins, like almonds or milk, or take a bit apple cider vinegar to lower the pH.
The enzyme in the stomach is called pepsin, which is produced in an inactive form to prevent the cells from hurting themselves. But once the pH drops sufficiently, the enzyme is activated, and chops proteins down into small chunks.
Small intestine: A magic place. It is not sterile, some (low numbers) lactic acid bacteria live here and protect the lining, which is highly specialized, and formed into folds on folds on folds, kinda like a cotton towel. The first bit is called duodenum, and bile is arriving here from the gallbladder, and the enzymes from the pancreas. Bile is produced fresh in the liver, and stored in the gall bladder. It is made out of cholesterin and bile acids. The green color comes from iron, called Bilirubin, which stems from digested and dead red blood cells. The body has to get rid of it somehow, and this exit seems to work the best. It gives your poop its brown color. The bile is necessary to turn the fats into something the body can take up, kind of like soap. The pancreas produces a shitload of enzymes to cut the chymus down into molecule size, and also produces bicarbonate to neutralise the acidic pH that came from the stomach. As inside the stomach, the enzymes are produced in an inactive form. If they would be active, it would digest your body. I had an ulcer close to the pancreas exit, and damn, this that hurt. If it is activated while still in the pancreas, it is called pancreatitis, and is highly, highly unpleasant.
The next parts of the small intestine are called jejunum and ileum, and are the place where the nutrients are taken up. The surface of these parts is enhanced by being folds on fold on fold (microvilli), and look like terry cloth towels. Even the cells are covered with folds (brush border). Sitting on these folds are more enzymes, lactase for example. This is because sugars need to be mono-sugars to be taken up. Also there: carrier and transporters, to get everything into the cells, and from there into the lymph and into the blood stream and the liver (nearly everything has to pass the liver first). On top of the brush border is a mucus layer, and on the mucus layer sit bacteria. They help with digestion, and also with the immune system, since you do not want any bigger peptides (2-10 amino acids) to reach the immune system cells, who would go into panic mode and allergies. The brush border is called that because the nutrients are kind of brushed into the mucus layer to reach the cells. If you have a bad bout of diarrhea, or antibiotics, you wash it all away: the bacteria that help with digestion, and also the enzymes that sit on the brushborder. This can lead to secondary lactose intolerance, which will go back to normal once it is recovered. But sometimes, shit happens, and you might even damage the cell lining, and peptides reach the immune cells...and you might end up with leaky gut syndrome, allergies, crohns...This is a very new field, because tech were not so good to have a look into the hidden secrets here. Doctors and scientist do not see and understand the impact and interactions of immune system, food, probiotics and diseases yet. Worse, some of it takes years or decades to develop, and research only scratched the surface during the last 10 years.
The chymus takes around 2-7 hours to pass this way.
Colon: Once most of the nutrients are gone, the colon removes the water from the chymus. At the same time, about 700 different types of bacteria ferment everything that is left: fiber, and often, lactose. They are the guys that produce the wind. They make some nutrients out of fiber and give it back to you, like some Vitamin Ks, and also some short chain fatty acids. They also lower the pH again and prevent bad bacteria to move in. They also protect the gut lining from damage, and increase the circulation. They love beans, apples and broccoli. Fun fact: it is now thought that the appendix is the place where your personal flora is stored. After antibiotics, or diarrhea, the bacteria that sleep there re-colonize the whole path again. The chymus can sit in the colon up to 72 hours, and even longer. By the end, a very high amount of your poop is dead bacteria, and the rest is indigestible. If there are too many nutrients, either you get constipation due to excessive gas, or some nutrients cling to water, which cannot be resorbed, which speeds up the passage. If there is barely any fiber in it, the bacteria do not survive, and the stool is impossible to form, which also leads to constipation. It does not matter if you only poop once a week or once a day, as long as it is regular, all is good.
Tomorrow: D is for Detoxification.
PS: please excuse writing mistakes. I need more coffee.